1. Field of the Invention
A friction clutch for selective direct coupling of a rotatable drive member to a rotatable driven member.
2. Description of Related Art
Friction clutches have use in many different applications for selective direct coupling of two rotatable members. In automotive applications, friction couplings may be found in various locations in the drivetrain of the vehicle. One application of the friction clutch is with a torque converter, which fluidly couples an engine to a transmission. The fluid coupling of the torque converter allows for slip and torque multiplication between the engine and the transmission, which is useful for accelerating the vehicle. However, when the velocity of the vehicle becomes steady, the motor and the transmission rotate at substantially the same angular velocity. The slip facilitated by the fluid coupling leads to energy losses when the vehicle is travelling at a steady velocity. The friction clutch has a piston coupled to the transmission and presenting a friction material and a cover coupled to the engine and presenting an engagement surface. The piston moves the friction material into engagement with the engagement surface to create a rotatable direct coupling between the engine and the transmission, which reduces energy losses between the engine and the transmission when the vehicle is travelling at a steady velocity.
The engagement of the friction material with the engagement surfaces causes a sudden direct coupling between the engine and the transmission, which produces wear between the friction material and the engagement surface. Furthermore, the sudden direct coupling between the engine and the transmission may cause the vehicle to lurch forward as any slight variance in angular velocity between the engine and the transmission becomes equalized. As such, there remains a need to provide an improved friction clutch.